Uninterruptible Power Supplies (UPS)

Uninterruptible power supplies (UPS) are backup batteries that provide emergency power to electrical systems in case power becomes unavailable. They are connected between a power source (such as an electrical outlet) and the equipment to protect (such as a motor or computer). There are two main types of uninterruptible power supplies (UPS): single-phase and three-phase. DC power supplies are also available. Single phase uninterruptible power supplies (UPS) provide power conditioning, back-up protection, and distribution for electronic equipment loads. They also prevent power disturbances from affecting equipment performance and life. As their name suggests, three-phase uninterruptible power supplies (UPS) operate in conjunction with existing electrical systems to provide power conditioning, back-up protection, and power distribution for loads that use three-phase power.

Specifications for uninterruptible power supplies (UPS) include volt-amp rating, watt rating, and input voltage range. The volt-amp (VA) rating is the maximum of volts multiplied by the number of amperes (amps) that the UPS can deliver. Note that the VA rating is not the same as the equipment’s power drain, which is measured in watts (W). The watt rating, which is less than or equal to the VA rating, is specified only if the number of volt-amps is unknown. The input voltage range, the precise identification of the electrical system, is critical to the proper selection of both single-phase and three-phase uninterruptible power supplies (UPS). 

Parameters to consider when specifying uninterruptible power supplies (UPS) include performance features, interfaces, surge suppression options, and typical applications. Performance features for uninterruptible power supplies (UPS) include self-diagnostics, automatic shutdown, and integral application software. Interface choices include serial, digital, parallel, modem, Ethernet, and PC card. Surge suppression options include UL 1449 rated surge protection, rated AC energy absorption, and maximum surge current. Typically, single-phase uninterruptible power supplies (UPS) are used with computers, bridges, routers, telecommunications devices, and other electronic equipment that requires continuous power. Three-phase uninterruptible power supplies (UPS) are used mainly with motors and power transformers.

There are three basic types of three-phase uninterruptible power supplies (UPS): on-line or double-conversion, line-interactive, and off-line or standby.  With on-line units, the load is supplied from a continuously-operating power converter that receives its input from a DC supply. This DC supply consists of a battery and a large battery charger, which are connected in parallel.  With line-interactive devices, the inverter works in parallel with conditioned-input AC power to supply power to the load (boosting or bucking), and only handles the full load power when the AC input power fails. With an off-line unit, the power is usually derived directly from the power line, until power fails. After power failure, a battery-powered inverter turns on to continue supplying power.

• Off-Line or Standby Uninterruptible Power Supplies (UPS)
  Off-line or standby uninterruptible power supplies (UPS) derive power directly from the power line (AC outlet) until the power sags or fails. When power sagging or failure occurs, a battery-powered...
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• On-line or Double-conversion Uninterruptible Power Supplies (UPS)
  On-line or double-conversion uninterruptible power supplies (UPS) use a constantly-operating power converter whose power source consists of a battery and battery charger that are connected in...
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• Line-interactive Uninterruptible Power Supply (UPS)
  Line-interactive uninterruptible power supplies (UPS) work in parallel with conditioned input AC power to supply power to the load (boosting or bucking), and only handle the full load power when the...
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Part Numbers for Uninterruptible Power Supplies UPS